3D Imaging of Gap Plasmons in Vertically Coupled Nanoparticles by EELS Tomography

Haberfehlner, Georg; Schmidt, Franz; Schaffernak, Gernot; Hörl, Anton; Trügler, Andreas; Hohenau, Andreas; Hofer, Ferdinand; Krenn, Joachim R.; Hohenester, Ulrich; Kothleitner, Gerald

doi:10.1021/acs.nanolett.7b02979

Cited by 33 publications

(38 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This characteristic generally applies to higher order cavity plasmon modes with a radial index larger than 1. The field maps in Figure agree well with the field distribution for gap plasmonic modes in vertical MIM structures in the work of Wei et al and Gerald et al12a,21…”

Section: Resultssupporting

confidence: 86%

Accessing the Hotspots of Cavity Plasmon Modes in Vertical Metal–Insulator–Metal Structures for Surface Enhanced Raman Scattering

Dai

Horrer

Adam

et al. 2020

Advanced Optical Materials

View full text Add to dashboard Cite

enhance the Raman scattering. [2,3] This process is called surface enhanced Raman scattering (SERS). The enhancement factor (EF) of SERS substrates is known to result from both electromagnetic and chemical enhancement. [4] It is widely acknowledged that the electromagnetic enhancement of plasmonic structures is the main EF contribution. The EF can be estimated by EF | | | | laser 2 Raman, where E  laser and E  Raman represent the field enhancement at the excitation (laser) wavelength and reemission (Raman) wavelength. [4] The near-field of plasmonic nanostructures can be particularly strong, when the field is concentrated in very small volumes. These socalled hotspots can occur, e.g., at the sharp tips of nanocones [2b] or in the gaps between different structures in a plasmonic multimer. Thus, in order to boost the enhancement of local electromagnetic (EM) fields, nanostructures with gaps on the scale of few nanometers, such as homodimers, [5] heterodimers, [6] trimers, [7] and vertical metal-insulator-metal (MIM) structures [8] were investigated extensively.In the case of lateral dimers or oligomers, the hotspots in the gaps between the single structures are readily accessible for detecting molecules. However, narrow gaps smaller than 10 nm are of poor reproducibility limited by the resolution of e-beam lithography (EBL). [5] On the contrary, vertical MIM structures with gaps down to the sub-nanometer scale can be obtained with thin film techniques such as atomic layer deposition (ALD) with high tunability and reproducibility. [9] Furthermore, a reproducible realization of gaps larger than 5 nm can be readily obtained with sufficient accuracy of the film thickness by established techniques such as evaporation or sputtering. [10] Due to their advantages in terms of large field enhancement and a straightforward fabrication method, vertical MIM structures, which consist of ordered nanodisc arrays on a gold film, separated by a thin dielectric layer, have attracted great attention in scientific research. [8a,11] Many groups have been concentrating on the theory of cavity plasmon modes and concluded that these modes result from the interplay of plasmonic modes and Fabry-Pérot cavities defined by the MIM structure. [11a,b,e,12,13] The cavity plasmon modes in vertical MIM structures have been exploited in applications such as structural colors, [11a,b,d] photovoltaics, [13] narrow-band perfect absorbers, [14] enhancing the spontaneous emission rate of dyes, [15] and enhanced infrared absorption. [16] It has been widely shown that the cavity In metal-insulator-metal structures such as Au nanodiscs on an Au film separated by a thin oxide spacer layer, the metal/insulator interfaces can form a Fabry-Perot cavity in which gap surface plasmons are confined. As a result, these cavity plasmon modes show the advantageous properties of strong field enhancement and very narrow resonance line shapes due to the confinement in a cavity. In this work, the hotspots of the electromagnetic near-field of cavity plasmon modes ar...

show abstract

Section: Resultssupporting

confidence: 86%

Accessing the Hotspots of Cavity Plasmon Modes in Vertical Metal–Insulator–Metal Structures for Surface Enhanced Raman Scattering

Dai

Horrer

Adam

et al. 2020

Advanced Optical Materials

View full text Add to dashboard Cite

show abstract

“…Due to the polycrystalline growth of the Ag in combination with the high Ag surface energy, 17 the MIM disks have nanometric surface roughness and rounded edges. 18…”

Section: Methodsmentioning

confidence: 99%

Plasmonic Dispersion Relations and Intensity Enhancement of Metal–Insulator–Metal Nanodisks

et al. 2018

Self Cite

View full text Add to dashboard Cite

We show that the plasmon modes of vertically stacked Ag–SiO2–Ag nanodisks can be understood and classified as hybridized surface and edge modes. We describe their universal dispersion relations and demonstrate that coupling-induced spectral shifts are significantly stronger for surface modes than for edge modes. The experimental data correspond well to numerical simulations. In addition, we estimate optical intensity enhancements of the stacked nanodisks in the range of 1000.

show abstract

“…Today, the controlled synthesis of metallic nanoparticles (NPs) with defined elemental composition, dimension, and shape, [ 1 ] the experimental characterization of plasmonic properties [ 2 ] as well as their simulation, [ 3 ] are comparably developed. When supracolloidal assemblies form from these well‐understood primary plasmonic entities, new collective properties emerge and complexity increases considerably.…”

Section: Introductionmentioning

confidence: 99%

Plasmonic Properties of Colloidal Assemblies

Roßner

König

Fery

2021

Advanced Optical Materials

View full text Add to dashboard Cite

for plasmonic NP assembly. These strategies typically involve using specific key components as linker spacer, which serve to guide the assembly process and control the supracolloidal structures: Metal oxide layers (such as silica), [4] biomacromolecular linkers (such as DNA), [5,6] as well as synthetic polymers are typical examples, each offering specific opportunities but also involving limitations (for a more detailed comparative discussion of these different preparative approaches, we refer to a recent review). [7] For example, metal oxide layers create a rigid, permanent barrier, and while this feature can be very beneficial for particular investigations, [4]

show abstract

3D Imaging of Gap Plasmons in Vertically Coupled Nanoparticles by EELS Tomography

Cited by 33 publications

References 27 publications

Accessing the Hotspots of Cavity Plasmon Modes in Vertical Metal–Insulator–Metal Structures for Surface Enhanced Raman Scattering

Accessing the Hotspots of Cavity Plasmon Modes in Vertical Metal–Insulator–Metal Structures for Surface Enhanced Raman Scattering

Plasmonic Dispersion Relations and Intensity Enhancement of Metal–Insulator–Metal Nanodisks

Plasmonic Properties of Colloidal Assemblies

Contact Info

Product

Resources

About